 /*******************************************************************************
  * Copyright (c) 2003, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.navigator;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.core.runtime.PlatformObject;

 /**
  * Provides utilities for working with adaptable and non-adaptable objects.
  *
  * @since 3.2
  */
 public class AdaptabilityUtility {

     /**
      * <p>
      * Returns an adapter of the requested type (anAdapterType)
      *
      * @param anElement
      * The element to adapt, which may or may not implement
      * {@link IAdaptable}, or null
      * @param anAdapterType
      * The class type to return
      * @return An adapter of the requested type or null
      */
     public static Object getAdapter(Object anElement, Class anAdapterType) {
         Assert.isNotNull(anAdapterType);
         if (anElement == null) {
             return null;
         }
         if (anAdapterType.isInstance(anElement)) {
             return anElement;
         }

         if (anElement instanceof IAdaptable) {
             IAdaptable adaptable = (IAdaptable) anElement;

             Object result = adaptable.getAdapter(anAdapterType);
             if (result != null) {
                 // Sanity-check
 Assert.isTrue(anAdapterType.isInstance(result));
                 return result;
             }
         }
         
         if (!(anElement instanceof PlatformObject)) {
             Object result = Platform.getAdapterManager().getAdapter(anElement, anAdapterType);
             if (result != null) {
                 return result;
             }
         }

         return null;
     }

 }

